Most modern communication devices, especially portable communications devices such mobile or cellular telephones, comprise at least two speakers. Typically there may be a loudspeaker located on the device, e.g. for audio media playback. This loudspeaker may be located towards the bottom of the device. In addition there may be an earpiece receiver speaker (i.e. a second speaker) at a different location on the device, for example towards the top of the device or otherwise at a location near where a user's ear may be expected to be in use (if not using an accessory such as a headset or using the device in a speakerphone mode). FIG. 1 for example illustrates a device 100, which in this example may be a mobile telephone, having a loudspeaker 102 at a first location on the device and also having an earpiece receiver speaker 104 at a different location.
In most common configurations the earpiece speaker and loudspeaker are used for different functions and typically the loudspeaker can generate a much greater sound pressure level (SPL) than the earpiece. The earpiece speaker is typically used as the output device during handset calls, when it is expected that the device is held next to the user's ear. The loudspeaker may be used as the output device during music playback and speakerphone mode calls.
The loudspeaker may typically be of the order of 8 Ohm, and may be driven for example by a 5V-10V boosted D or G class amplifier which is capable of driving around 4 W into the speaker. The earpiece may typically be of the order of 32 Ohm, and may for example be driven by a 2.5V A/B class amplifier which is capable of driving around 100 mW in to the earpiece speaker.